Device and method for the widening and forming of a can body

ABSTRACT

The invention relates to an apparatus for spreading and shaping can bodies, having a pin-like shaping tool that is forced from one end into the can body to be widened and a counter tool.  
     According to the invention the counter tool is also a pin-like shaping tool insertable from an opposite end into the can body, the shapes of the ends of the two pin-like shaping tools being the same or complementary according to the desired shape.

[0001] The invention relates to an apparatus for spreading and shapingcan bodies, having a pin-like shaping tool that is forced from one endinto the can body to be widened and a counter tool.

[0002] The invention also relates to a method of spreading and shapingcan bodies where a pin-like shaping tool is forced into a can body andmoved toward a counter tool.

[0003] Such an apparatus and method are described in German 100 40 173.This apparatus has a hard and massive shaping block made of steel oranother hard material and of cylindrical cross section that has overmost of its length a large diameter corresponding to an inside diameterof the spread can body and near its upper end a frustoconical portion.Above this frustoconical portion is a short region of smaller diameterthat corresponds to the inside diameter of the unspread can body. Theshaping block is used by forcing it into the can body to be spread. Theshaping block can further have on its lower end a tool for forming aflange and constituted as a steel plate that is formed on its upper facewith an annular groove of undercut section that is reached by the lowerend of the cylindrical can body as it is being spread so as to engageit. The counter tool according to German 100 40 173 serves for forming aflange on the upper end of a can and also is formed as a steel platehaving a face turned toward the shaping block and formed with an annularundercut groove having a small annular overhanging edge that forms theinner flank of the groove. The overhanging edge engages during thespreading operation the upper end of the can body. As the shaping blockis forced into a readied can body, the can body is shaped by the outersurface of the shaping block with its diameter being increased andformed in a single step with a so-called “neck in.” The grooves of thetwo steel plates form the two end rims of the can. The can-body shape isthe same at the end of the operations as the outer surface of theshaping body, that is the can body has a cylindrical upper part abovethe neck-in region.

[0004] To distinguish over competitors, the fillers want individuallydesigned cans. The present mass-production method of shaping can bodiesis mechanical expansion or spreading. The tool for doing this iscomprised of a plurality of segments arranged in a cylinder and formingan outer surface of the desired shape. The tool is fitted into thewelded cylinder and is spread radially outward by means of an internalcone so as to deform the can body. The disadvantage of this method isthat the finished can body is somewhat polygonal, the can-body materialis locally very greatly stretched, the rim is irregular, and thespreading does not extend to the rim and thus there is not a preciselyshaped edge.

[0005] Other methods use a shape-imparting hollow die in which the rimsare deformed. Highly pressurized air or a water stream serves for thedeformation. Such methods are expensive, slow, and inflexible.

[0006] Embossing the desired shape can also be done by so-calledspin-flow shaping which is actually a roller-pressing operation whichdoes not spread but instead reduces the diameter of the weld rim. Thismethod can only produces rotation-symmetrical shapes.

[0007] Based on this state of the art, it is an object of the presentinvention to provide a method and apparatus of the above-described typethat produces cost-efficient, flexible, and easily changed can-bodyshapes, including nonrotation-symmetrical shapes. The machine elementsserving this purpose should be as robust as possible and permitdeformations right up to the edge of the can rim.

[0008] This object is achieved by the apparatus of claims 1 to 7 and themethod of claim 9.

[0009] According to the invention the can blank has a diameter that isequal to or smaller than the smallest diameter of the finished can. Incontrast to the state of the art a first embodiment of the invention hastwo pin-like shaping tools that are forced into opposite ends of the canbody so as to deform and spread the can body until the ends of thepin-like shaping tools reach an end position. The cross-sectionalprofile of the two pin-like shaping tools have at least at their outerends a region that is radially inset from other regions. This can be afrustoconical pin end or tangentially interengaging rounded surfaces ora combination of the two, and on the outer surface it is possible tohave a noncircular cross section or a combination of these shapes. Thepin ends have a maximum diameter that is smaller than, equal to, orslightly larger than the diameter of the can blank. In particular thecross section at least of the end tapers outward. The pin end faces caneither be perpendicular to the longitudinal tool axis, inclined, or evenwavy or otherwise shaped. This latter formation allows insets to beformed in the can body that extend at angles, are wavy, or otherwisedeviate from perpendicular to the axis.

[0010] An object of the present invention is also a method and use ofthe described pin-like shaping tools.

[0011] Further embodiments of the invention as well as advantages aredescribed with reference to the drawing. Therein:

[0012]FIG. 1 is a schematic representation of two pin-like shaping toolsthat are movable toward each other through holes in strippers, shown inthe starting position before can-blank deformation;

[0013]FIG. 2 is a view like FIG. 1 with the can-shaping tools movedpartly together;

[0014]FIG. 3 is the end position of the shaping tools in which the canbody has its final shape;

[0015]FIG. 4 is a side view of the can profile produced according toFIGS. 1 to 3;

[0016] FIGS. 5 to 9 are differently shaped can bodies; and

[0017]FIG. 10 is a stackable can body with a rotation-symmetricaldecorative shape.

[0018] As already mentioned, the can blank is welded to a diameter thatis equal to or less than the smallest diameter of the finished shape andthen is deformed by forcing into one or both ends shaping tools toimpart to it the final greater diameter of the outside of the shapingtool. The formation of the pin ends and of the pins is the same as thedesired shape and the can geometry. If according to the desired finishedshape, the pin end is of equal or greater diameter than the insidediameter of the welded can blank, the blank end is slightly spread in afirst step so that the pin can be forced automatically into it.

[0019] As shown in FIG. 1, two pin-like shaping tools 1 and 2 that canpass through holes of spaced strippers 3 and 4 serve as shaping toolsfor a can blank 5 whose ends are slightly frustoconically spread so thatthe outer ends of the shaping tools 1 and 2 can be fitted into them. Theopen blank 5 is positioned by unillustrated means known in the artbetween the strippers 3 and 4 and is aligned coaxially with the axes 6of the shaping tools 2 shown in their upper and lower end positions.

[0020] As shown in FIG. 2, the shaping tools 1 and 2 are moved togetheras shown by arrows 7 and 8 so that they spread the can blank 5 untilthey reach the end position of FIG. 3. The shape of the shaping toolshas been imparted to the can blank 5 which is formed in its lower thirdwith an outwardly open recess 9 that is formed by the tapered ends ofthe shaping tools. The ends of the shaping tools in the FIG. 3 endposition abut each other flatly. After deforming the can blank 4 theshaping tools 1 and 2 are pulled apart so that the deformed blank isleft between the stripers 3 and 4 and can then be carried off by aconveyor as is known in the art. FIGS. 1 to 3 show that not only theshaped end of the shaping tools but their entire outside shape has beenimparted to the blank 5 so that not only the smooth round shapes of FIG.4 and 4 can be produced, but also nonround shapes corresponding to FIGS.6 and 7 can be produced as well as longitudinally shaping correspondingto FIG. 8 or FIG. 9 in addition to combinations of these shapes.

[0021]FIG. 5 shows a spread blank 10 with a shape having a protectiverecess 11 that is formed by pushing the lower shaping tool almost to theupper end of the blank and making the upper shaping tool much shorter.In this case the end faces of the tools abut on a plane perpendicular tothe longitudinal axis 6.

[0022]FIG. 6 shows a spread blank 12 with an asymmetrical wave-likedecorative shape. The recess 11 is annular but not orthogonal to thelongitudinal axis 6, but inclined thereto and is also wavy. This iscreated by two pin-line shaping tools with correspondingly shaped endswhose end faces meet at an angled or wavy surface extending across theaxis 6 and inclined or crossing a plane. These tools according to theinvention only spread the can blank so have no insets and theirfrustoconical ends meet according to the desired shape and position ofthe recess.

[0023] The blank 14 of FIG. 7 is also asymmetrical and has two nonlinearregions 15 and 16 in which they taper to a smaller diameter which in theintermediate region 17 is constant according to the shape of the pinends. In general the shape can be oriented according to the drawing.

[0024] In the can blank 18 of FIG. 8 there is a combination of arotation-symmetrical decorative shape and longitudinal profiling 19 thatare made by the outer surface of the shaping tool. In order to producethis can blank two pin-like shaping tools are used whose end faces abutinside the can blank at a plane 20 in the end position. In addition tothe inset 21 the lower shaping tool also makes a lower large-diameterregion 22 that is the same or different diameter as the uppercylindrical region 23 of the blank.

[0025] The can blank 24 has an outer surface that flares outward toupper and lower end regions 25 and 26 from a central plane 27, that isthe shape is basically concave.

[0026]FIG. 10 shows how two can blanks 5 according to FIG. 4 can bestacked. The same is also true for the other can blanks.

[0027] The above-described pin widening method has the followingadvantages over the prior-art spreading method:

[0028] The spread blank, depending on the pin shape and not includinglongitudinal profiling, is circularly round and not inherentlypolygonal.

[0029] In addition the sheet metal is stretched uniformly so that morestretching is possible with the same metal deformation. There are nosignificant length changes. The shaping extends right to the blank end.

[0030] In addition there is a desired uniform reduction in the thicknessof the sheet metal in the cylindrical part, while in the stressed shaperegion the original sheet thickness is retained.

[0031] The shaping tools that are used are simple, robust, and easy toretrofit to or install in existing equipment, when different shapes areneeded.

[0032] The shapes shown in FIGS. 1 to 10 can be varied greatly, thelimits to the shapes being small, with respect to the use of the sheetmetal and lacquer. As already stated, one is not restricted to recessedformations.

1. An apparatus for spreading and shaping can bodies (5), having apin-like shaping tool (1) that is forced from one end into the can body(5) to be widened and a counter tool (2), characterized in that thecounter tool (2) is also a pin-like shaping tool insertable from anopposite end into the can body (5), the shapes of the ends of the twopin-like shaping tools (1 and 2) being the same or complementaryaccording to the desired shape.
 2. The apparatus according to claim 1,characterized in that the shape of the two pin-like shaping tools (1 and2) at their ends has in regions inset toward the longitudinal pin axis(6) from other regions.
 3. The apparatus according to claim 1 or 2,characterized in that the pin ends have a maximum diameter that is lessthan, equal to, or slightly greater than the diameter of the unspreadcan blank (5).
 4. The apparatus according to one of claims 1 to 3,characterized in that the pin ends taper outward axially at their outerends.
 5. The apparatus according to one of claims 1 to 4, characterizedin that the pin end faces meet at least partially in regions notorthogonal to the pin longitudinal axis (6).
 6. The apparatus accordingto one of claims 1 to 5, characterized in that the pin outer surfacesdeviate at least locally from a cylindrical shape.
 7. An apparatus forspreading and shaping can bodies (5), having a pin-like shaping tool (1)that is forced from one end into the can body (5) to be widened and acounter tool (2), characterized in that the pin outer surfaces deviateat least locally from a cylindrical shape.
 8. The apparatus according toone of claims 1 to 7, characterized in that the pin-like shaping toolsare movable relative to strippers (3 and 5).
 9. A method of spreadingand shaping can bodies (5, 10, 12, 14, 18, and 24), wherein a pin-likeshaping tool (1) is forced from one end into the can body (5) against acounter tool (2), characterized by use of an apparatus according to oneof claims 1 to 8.